mac80211: Prevent AP probing during suspend

Submitting AP probe/null during suspend can cause unexpected
disconnect on resume because of timeout waiting for ack status:

wlan0: Failed to send nullfunc to AP 11:22:33:44:55:66 after 500ms, disconnecting

This is especially the case when we enter suspend when a scan is
ongoing, indeed, scan is cancelled from __ieee80211_suspend, leading
to a corresponding (aborted) scan complete event, which in turn causes
the submission of an immediate monitor null frame (restart_sta_timer).
The corresponding packet or ack will not be processed before resuming,
causing a timeout & disconnect on resume.

Delay the AP probing when suspending/suspended.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1634805927-1113-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index c3b8590..5666bbb 100644 (file)
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1241,6 +1241,9 @@ struct ieee80211_local {
         */
        bool suspended;
 
+       /* suspending is true during the whole suspend process */
+       bool suspending;
+
        /*
         * Resuming is true while suspended, but when we're reprogramming the
         * hardware -- at that time it's allowed to use ieee80211_queue_work()

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 16ef739..54ab0e1 100644 (file)
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2589,6 +2589,13 @@ static void ieee80211_mgd_probe_ap(struct ieee80211_sub_if_data *sdata,
                goto out;
        }
 
+       if (sdata->local->suspending) {
+               /* reschedule after resume */
+               mutex_unlock(&sdata->local->mtx);
+               ieee80211_reset_ap_probe(sdata);
+               goto out;
+       }
+
        if (beacon) {
                mlme_dbg_ratelimited(sdata,
                                     "detected beacon loss from AP (missed %d beacons) - probing\n",

diff --git a/net/mac80211/pm.c b/net/mac80211/pm.c
index 7809a90..0ccb570 100644 (file)
--- a/net/mac80211/pm.c
+++ b/net/mac80211/pm.c
@@ -27,6 +27,9 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
        if (!local->open_count)
                goto suspend;
 
+       local->suspending = true;
+       mb(); /* make suspending visible before any cancellation */
+
        ieee80211_scan_cancel(local);
 
        ieee80211_dfs_cac_cancel(local);
@@ -176,6 +179,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
        /* need suspended to be visible before quiescing is false */
        barrier();
        local->quiescing = false;
+       local->suspending = false;
 
        return 0;
 }